Like she said "I am not selfless, I am brave" she would have chosen dauntless no matter what

before the test, i think she would have chosen to stay with her family.

I suspect that she was already thinking about choosing Dauntless before the aptitude test.

There was obviously always a part of her that she felt was Dauntless, and it's like Tris said herself "I am selfish. I am Brave." She may not have wanted to leave her family but she still made that decision and I don't think the aptitude test would have changed her mind that much.

i was already pretty sure that she would pick dauntless (remember when she couldn't stop watching the dauntless kids at school)

i think she wouldve chose Abnegation because she didnt want to let her family down

I know for sure she wouldn't have stayed in Abnegation because she literally did not feel like she fit.

You could tell that she secretly wanted to be dauntless, even before the aptitude test. she watched them every morning, and constantly referred to them.

Remember she told herself
'traded cowardice for cruelty, traded weakness for ferocity'
she was a coward before so she would have chosen Abnegation
if that doesn't make sense then think about it